i had this problem too & here are the steps on how to fix it.
1) go to the Control Panel
2) click on Add & Remove Program
3) find League of Legends
4) Un-install it
5) Restart your computer
6) Download it again

Good Luck!

The same problem is persisting.

Bump.

I just got banned because of this. I can log in, but I couldn't reconnect to the game.
disabled wiidows firewall, 3rd party firewall, and restarted the computer. i am not behind a router. i played 4 games until this happened...wtf

Bump.

I played 4 games until this happened. on the 5th i selected my champion, but it never got to the loading screen.

I disabled my windows firewall, 3rd party firewall, and restarted.

I am not behind a router.

I just got banned for this?!?!

update to the above message. It is definitely on Riot Games side. I was able to log into another account and play a couple of games. perhaps my school's firewall is blocking some of your game servers? but only particular ones, because it just came up out of the blue?

just happened to me. game started but there was only a black screen for about 30 seconds and then the error message came up. restarted client, didn't work. restarted computer, didn't work. just feel bad cuz now everyone thinks i just bounced out on the game.

hoping for a future quick fix!

I think i have found a fix. Go to windows firewall with advanced options. Then go to inbound rules. Scroll down, you should see three League of legends names. Only one of mine was activated. After i activated the other two, it started to work for me!

dude i have the same problem just put rety aand it will conect

Bump

bump